1. Field of the Invention
The present invention relates to a coating device and a coating method.
2. Description of the Related Art
For example, upon foamig a thin film such as a resist film on various substrates such as a semiconductor substrate, a glass substrate forming a liquid crystal panel, and a substrate forming a hard disk, a coating device is used to form the coating film on the substrate while rotating the substrate. In the coating device, in general, the substrate is laid down so as to be parallel to a horizontal plane and the substrate is rotated while the lower substrate surface is held.
Meanwhile, in the substrate used to form the hard disk, for example, it is necessary to coat the liquid material on both surfaces thereof. In the case of this kind of substrate in which both surfaces are required to be coated with the liquid material, it is not possible to hold the lower substrate surface. For this reason, Patent Reference 1, for example, discloses a technology in which the substrate is rotated while the substrate is held by a holding piece.
In the case where the liquid material is coated on both surfaces of the substrate when the substrate is laid down, the coating conditions between the top and bottom surfaces of the substrate are different. For this reason, the state of the thin film formed on the top surface of the substrate may be different from the state of the thin film formed on the bottom surface thereof. To the contrary, there has recently been proposed a technology in which the liquid material is simultaneously coated on both surfaces of the substrate in an upright (i.e. vertical) state.
[Patent Reference 1]
Japanese Unexamined Patent Application, First Publication No. Hei 7-130642
It is required that the liquid material at the outer periphery of the substrate be in a satisfactory coating state when the liquid material is coated on the substrate. As a matter of course, a satisfactory coating state is similarly required when the liquid material is coated on the substrate in an upright state.